Gas exploder system



United States Patent Inventor William J. Gundlach [56] References CitedFulshefll', Texas UNITED STATES PATENTS P g fl 1969 1,899,970 3/1933McCollum 340 155 Fled 0 2,994,397 8/1961 Huckabay l8 1/0.5 gg'ggzfigz fg3,058,540 10/1962 Simpson l8l/0.5 Patented 3 1970 3,256,952 6/1966Crider et al l8l/0.5 Assignee Geo Space Corproation Primary Examiner-Rodney D. Bennett. Jr.

Houston, Texas 7 Assistant Examiner-Daniel C. Kaufman a corporation ofTexas ABSTRACT: This invention relates generally to gas explodersincluding a combustion chamber, for receiving a mixture of GAS F ig gcombustible gases, and a flexible conduit coupled to the 8 Chums rawmgchamber and adapted for carrying a detonating shock wave US. Cl 181 /0.5into the combustion chamber, thereby igniting the gases in the Int. ClG0lv 1/04 combustion chamber, and/or carrying a uniformly mixed gasField of Search l8l/0.5(1C) mixture into the combustion chamber.

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10 /4 I00 30 0100/26 0 REMOTE V 6 IGNI TER l2 6A5 MIXTURE 3/ D. C. POWERINVISN'I'UR.

WILL/AM J GUNDLACH Tii7 3 y ATTORNEY GAS EXPLODEIR SYSTEM This is acontinuation of application Ser. No. 766,412, filed Oct. 10, 1968 andnow abandoned.

BACKGROUND OF THE INVENTION Gas exploders are used in many technicalfields such as in seismic exploration, metal forming, pile driving, etc.The proper operation of a gas exploder is dependent upon the existencein the combustion chamber of a uniform, suitably proportioned mixture offuel and oxidizer gases. Even when the fuel and oxidizer gases areadmitted to the combustion chamber at the proper ratio, in thecombustion chamber the gas mixture is not always consistently uniform.For example, there may be small areas or pockets particularly at edgesand corners in the chamber wherein the mixture is nonuniform. When thegases in the combustion chamber become ignited, the detonation in suchpockets is either at some undesired velocity or practically nonexistent.Consequently, a part of the charge of fuel and oxidizer gases may bewasted, or what is worse, a relatively weak detonation results from theentire charge. In the geophysical exploration field, for example, faultyor relatively weak detonations cause inferior records.

While this invention is particularly well suited to arts other than theseismic art, it will hereinafter be described with particular referenceto gas exploders used in the seismic prospecting art. It should beunderstood, however, that the invention will find important applicationsin other fields, as previously mentioned.

Typically in seismic prospecting, pulses of acoustic energy aresequentially generated in the area under investigation. The downwardlydirected acoustic waves give rise to reflected and/or refracted waves atthe formation interfaces encountered in the downward path of travel bythe transmitted waves. Sensitive transducers such as geophones orhydrophones are suitably emplaced for transforming the returned acousticwaves into corresponding electric signals which are applied to suitablerecording and displaying apparatus.

Generally known seismic gas exploders include an enclosed or open endedcombustion chamber containing an igniter, typically a spark plug, inlettubes for admitting fuel and oxidizer gases, and often exhaust tubes toallow the products of combustion to escape to the atmosphere.

While the use of seismic gas exploders has increased significantly inthe last few years, certain problems have been encountered in their use.

The improper, partial or incomplete mixing of the fuel and oxidizergases in the combustion chamber cause the gas exploder to misfire or themixed gases to burn rather than to detonate, or to detonate but with arelatively low order of energy yield.

Generally in known gas exploders, the mixing of fuel and oxidizer gaseswas done in the combustion chamber itself. The spark plug or igniterformed a part of or was mounted on the gas exploder. The dimensions of atypical seismic gas exploder are relatively large compared to thedimensions of the inlet fuel and oxidizer lines. Therefore, poor gasmixing frequently occurred in the combustion chamber, giving riseoccasionally to low energy detonations.

Known seismic gas exploders also suffer from field servicing problems.it will be appreciated that when the igniter or spark plug and inletvalves are mounted in or on the exploder, their servicing andmaintenance in the field are rather difficult, particularly in the casewhere the gas exploders are used in subzero weather or under water.

Also in marine seismic work, the gas inlet lines present anobjectionable drag and even cause undesirable noise.

SUMMARY OF THE INVENTION The gas exploder system of the presentinvention eliminates the foregoing and other problems by providingthrough a flexible conduit thoroughly mixed fuel and oxidizer gases tothe inner volume of the combustion chamber. The gas mixer is positioneda distance from the combustion chamber as on board ship or near thecabin of the vehicle carrying the gas exploder. The detonation in thecombustion chamber may be initiated by sending a detonation shock wavethrough the flexible conduit into the combustion chamber or thedetonation may be initiated by a spark plug mounted on the exploder in aconventional manner. The flexible conduit may be several feet long oreven a lOO and more feet long. Also, several gas exploders may be firedfrom the same or independent igniters simultaneously or in apredetermined time pattern by taking into consideration the travel timeof the detonation shock waves through the flexible conduits.

Accordingly, it is a main object of the present invention to providethrough a flexible conduit the combustion chambers in gas exploders withmixtures of thoroughly mixed gases from a remotely positioned gas supplysource.

It is another object of the present invention to use the same flexibleconduit both for carrying detonation shock waves and the thoroughlymixed gases into the combustion chambers.

It is yet another object of this; invention to provide a single assemblyadapted to be mounted remotely from the gas exploder and connectedthereto by a flexible tube, the assembly having means for thoroughlymixing the fuel and oxidizer gases and igniting the mixed gases tothereby set up detonation shock waves through the flexible. tube.

A still further object of the present invention is to allow theconstruction of gas exploders which are relatively inexpensive tomanufacture, easy to maintain in good repair, and adapted for use undersevere environmental conditions and under water.

Yet another important object of the present invention is to provide agas exploder system including a combustion chamber, a remotelypositioned fueling assembly including a gas mixer and igniter, and aflexible tube coupling the assembly to the chamber thereby allowingrelative displacement between the assembly and the combustion chamber.

Gther objects and advantages of the present invention will becomeapparent from the following detailed description when considered inconjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THEDRAWINGS FlG. l is a block diagram of the gasexploder system in accordance with the invention;

FIG. 2 is a showing, partly schematically and partly in cross section,of a preferred embodiment of the system shown in FIG. 1;

FIG. 3 is a view in cross section of a section of the gas mixer shown inFIG. 2; and

FIG. 4- is a view in cross section of a portion of the flexible tubeshown in FIG. 2.

Referring now to the drawings, and more particularly to FIG. ll, asource of oxidizer gas typically a container 10 of oxygen, a source 12of fuel gas such as a tank of propane or the like, are connected throughsuitable tubings 14 and 16, respectively, to an assembly, generallydesignated as 24). Also connected to the assembly 2b is a suitableelectric energy source such as a battery 22 through a switch 23 and aconductor 24. A gas exploder 26 having an inner volume forming acombustion chamber 28 is coupled to the assembly 20 through a flexibleconduit or tube 30, the length of which may vary from a few feet to upto and more feet. The battery 22 may also be connected through switch 23to a spark plug 31 on exploder 26 when local rather than remote andflexible firing is desired. Since the local firing technique isconventional no further description thereof is necessary.

As previously mentioned, the gas exploder 26 may be used in variousfields such as metal forming, pile driving, and seismic exploration. ineach field the exploder has a particular configuration. Since theinvention does not reside in the gas exploder per se, no detaileddescription thereof is believed to be necessary.

In the seismic art several gas exploder-s are widely known under varioustrade names such as DINOSEIS and AQUAPULSE. These gas exploders aredescribed in the technical and patent literature.

Seismic gas exploders are typically carried if for land work on specialpurpose off-the-road carriers and if for marine work on seismic ships.It will be readily appreciated that in accordance with this inventionthe fuel sources 10, 12, the electric energy source 22, and the assemblycan all be carried on board the carrier or ship, thereby allowingrelative movement between the gas exploder 26 and the assembly 20.

Referring to the preferred embodiment shown in FIG. 2, tube 14 isconnected through a strainer 36, an orifice 38, a solenoid operatedvalve 40,.a check valve 42, a pipe 44, a T- coupler 46, a pipe 48 to theinlet port 51 of an assembly block 50. A suitable opening 52 through theblock 50 allows the gases to enter a gas mixer or turbulator assembly 54through outlet port 56.

The other line 16 feeds into the T-coupler 46, also through a strainer60, an orifice 62, a solenoid operated valve 64, and a check valve 66.The strainers prevent the collection of foreign matter in the gas flowproportioning orifices 38, 62. These orifices have suitable relativethroat sizes, which may be adjusted if desired, to provide apredetermined detonating gas mixture into the turbulator 54. Thesolenoid operated valves 40, 64 have suitable pressure and transmissioncapabilities. The check valves 42, 66 may be of the spring-loaded typecapable of withstanding the peak back pressures of the detonating shockwaves, thereby preventing damage to the relatively fragile, low-pressuresolenoid valves 40, 64. since these components are commerciallyavailable and their respective functions are well known, no furtherdescription thereof is believed necessary for an understanding of thisinvention.

The main function of the turbulator assembly 54 is to allow thoroughmixing of the fuel'and oxidizer gases from sources l0, 12. A suitableturbulator can be made of inexpensive tubing, for example in U-shapedform. Two constrictions 70, 72 are provided as shown. The constrictions70, 72 are arranged by inserting two tubular inserts 74, 76,respectively, having orifices 78, 80 of reduced diameters.Experimentally the diameters 78, 80 are determined for optimumturbulance and hence mixing of the incoming gases.

For remote firing any desired igniter or igniter system may be employed.For simplicity-a spark plug 84 is shown mounted at the bottom of theassembly mounting block 50. The electrodes 86, 87 of the spark plug 84are exposed to an internal channel 88 coupling an inlet port 90 to anoutlet port 92 which is connected to the flexible tube 30. Theturbulator is therefore coupled between ports 56 and 90. Connected tothe center electrode 86 is a suitable ignition coil 94 energized by anelectrical source 96 through a switch 97. The spark plug, ignition coiland switch may be of the same types as those used in the automobileindustry since they are generally available and are relativelyinexpensive.

In FIG. 4 is shown a section of a commercially available flexible tubemade by Flexonics, known in the trade as corrugated metal hose Series400 8/8. As can be seen from the drawing, the flexible pipe has abellows type construction and is fabricated from stainless steel withclose pitch annular corrugations. The hose has a maximum workingpressure range specified by the manufacturer from full vacuum to 4,500p.s.i.g. depending on size. it can withstand temperatures up to 1,500 F.Other flexible hoses could be employed and for some applications plastichoses made for example of Teflon could also be used.

in operation, the seismic sound source 26 is placed in position to tireeither on land or under water, the oxidizer and fuel supply sources 10,12 are turned on and their pressures adjusted to about the same value.The operating pressure is of course determined by the fuel supply systemcharacteristics such as tubing size, valve port areas, etc., by the fuelvolume requirements of the seismic sound source itself, and by the timeavailable for fillingthe combustion chamber between successiveexplosions. These factors are usually known and are taken intoconsideration in the design of the fuel supply system.

With fuel and oxidizer pressures established, the solenoid valves 40, 64are opened, permitting fuel and oxidizer to flow through the checkvalves 42, 66, respectively, and through the T-coupling 46, line 48,opening 52 in the mounting block 50, and into the turbulator assembly54. In the turbulator assembly the restrictions 70 and 72-cause thegases to become thoroughly mixed. This mixture is fed through theopening 88 into the flexible tube 30. The thoroughly mixed gases arethus admitted into the gas exploder 26 through the flexible tube 30.

Valves 40 and 64 are held open until the combustion chamber 28 insidethe exploder 26 is fully filled at which time the valves are closed andthe mixture ignited by momentarily closing and opening switch 97.

Upon becoming ignited at the electrodes of the spark plug 84, adetonation shock wave is formed and moved through the flexible tube 30into the gas exploder 26 where it detonates the mixture of fuel andoxidizer charge in the combustion chamber 28. The resulting detonationgenerates an acoustic wave useful for obtaining seismic reflectionand/or refraction waves.

The detonation shock wave also moves in the direction opposite from thecompliant tube 30 and proceeds backward through the turbulator 54 andthe connecting fuel supply line system until it reaches check valves 42,66. The check valves 42,66 which are normally closed, protect therelatively lowpressure solenoid operated valves 40, 64 and the remainingof the supply fuel line system connected thereto.

After the charge in the seismic gas exploder 26 is detonated and theproducts of combustion exhausted through the exhaust system, generallydesignated as 100 (FIG. 1), the solenoid valves 40, 64 may be reopenedto supply a fresh charge of thoroughly mixed gases into the seismic gasexploder 26 for the next cycle of operation.

It will be readily appreciated that the foregoing described preferredembodiment is simple to construct and relatively easy to service. Theturbulator assembly 54, through its restrictions 74, 76 and theconnecting tubing, allows thorough mixing of the fuel and oxidizergases. The gas supply lines, remote igniter, and gas mixer assembly 20can be mounted on board ship or near the cabin of the special purposecarrier where they can be relatively easily inspected and serviced.Other advantages of the system will be readily apparent to users of gasexploders. For example, in marine seismic exploration it is desired tohave a minimum of lines coupling the marine seismic energy source to theseismic ship to prevent drag and the generation of undesirable noise. Byadapting the system of the present invention both drag and noise arereduced considerably.

Several gas exploders can be connected in series and/or series parallelcombinations and supplied from a single igniter and mixer assembly 20(See FIG. 1).

Therefore, while preferred embodiments have been disclosed, it will beunderstood by those skilled in the art that modifications may be madetherein without departing from the principles of the present invention,and said invention is to be limited only by the claims appended hereto.

1 claim:

1. A seismic gas exploder system comprising:

a combustion chamber;

gas supply means;

at least one flexible conduit coupling said gas supply means to saidchamber; said conduit defining a combustible gas mixture flow pathextending to said chamber;

gas igniter means remotely positioned in one portion of said pathupstream of said conduit;

said conduit permitting, during operation of said system,

relative displacement between said chamber and said igniter means; and

5. The system of claim a wherein said igniter means is a spark plug.

6. The system of claim 4 and further including check valve meanspositioned upstream of said ignite: means.

'7. The system of claim 5 and further including controllable valve meanspositioned upstream of said check valve means.

8. The system of claim '7 wherein said gas supply means includes asupply of at least one fuel gas and of at least one oxidizer gasconnected to feed said flow path.

